A charged particle beam column directs a beam of charged particles to a specimen supported on a stage, for machining or imaging the specimen. Often, two charged particle beam columns are used in tandem (a “dual beam system”), with an electron beam being used for imaging and a focused ion beam being used for machining. Typically, in a dual beam system, there is a gap of at least 13 mm between the lower end of either column and the specimen. This gap permits a light source placed to the side of the column to shine light obliquely on the specimen. Also, one or more gas nozzles can be introduced into the gap, to introduce desired gasses directly toward the specimen.
Recently, it has been perceived that an advantage could be obtained by placing the end of the column much closer to the specimen, and by making the end of the column flat, rather than conical. This design concept, however, prevents gas from being delivered to the specimen because there is no place for a gas nozzle in the small gap between column and specimen. Likewise, light from a light source to the side of the column would be blocked from reaching the specimen, by the bottom of the column. As there are some production techniques that require light or gas or both to be delivered to a specimen, the design concept cannot be practical unless some way is found to deliver these elements to the specimen, despite the presence of the lower end of the column, so close to the specimen.